Primarily microlenses are used for devices which require an optical focusing means, such as for example cameras and mobile phones. As a result of miniaturization pressure, the functional components are becoming increasingly smaller; this also applies to microlenses of the generic type. The further the microlenses are to be miniaturized, the more difficult their optically correct production becomes because at the same time there is enormous cost pressure for microlenses to be ideally produced in large-scale production.
In the prior art microlenses are produced on a carrier substrate by various production methods, as shown for example in U.S. Pat. Nos. 6,846,137 B1, 5,324,623, 5,853,960 and 5,871,888. It is common to all the aforementioned methods that a certain thickness is necessary in principle and the light which passes through the microlens must pass through not only the lens, but also the carrier substrate.
As a result of the simultaneously required high quality and the demands for higher resolution with simultaneously high brilliance, which depends among others on the thickness and the number of optics along the optical axis, therefore the beam path, further optimization of the microlenses according to the prior art is desirable.
Moreover there is a requirement for radiant efficiency which is as high as possible and which is decisive especially for micro optics systems, since the image sensor occupies a generally very small area on which light is incident.
U.S. Pat. No. 6,049,430 shows a lens which has been inserted in an opening of a carrier substrate, and the production process shown in FIG. 2 requires a plurality of steps and is therefore complex and due to the production accuracies which can be attained here would be too inaccurate for the aforementioned requirements. The plurality of materials to be used is also a disadvantage.